Recent advances in DNA analysis allow us to identify an unprecedented number of insect samples collected by mass sampling techniques such as insect traps. In these circumstances, a preservative that can be applied from trap to storage is necessary to prevent degradation of DNA before analysis and save on the cost of labor for collecting insects from traps. Propylene glycol has a prominent feature as a trap solution. We aimed to examine the DNA preservability of 98% propylene glycol at 2 weeks and more than 6 months after initial collection in comparison with 99.5% ethanol, which is commonly used for storage of specimens for genetic analysis. We compared amplification performance of PCR targeting a specific region of the mitochondrial cytochrome c oxidase subunit I (COI) gene in the orders Hymenoptera, Diptera, and Coleoptera using two extraction methods varying in extraction efficiency. Even after 6 months, more than 75% of samples were recognized to have succeeded in PCR amplification irrespective of preservatives by the extraction method with higher extraction efficiency. It suggested that mitochondrial DNA was preserved in both solutions. However, dim bands in the electrophoreses of PCR products increased with time in extracts by another method with lower extraction efficiency. In Diptera and Coleoptera, the rate of dim bands increased more rapidly for ethanol‐preserved than for propylene glycol‐preserved specimens, indicating higher DNA preservability of propylene glycol over time for these taxa. On the other hand, in Hymenoptera, the preservatives did not affect PCR amplification performance. Considering its safer characteristics and high DNA preservability in a wide range of taxa, propylene glycol can be a promising solution from trapping of insects to storage for genetic analysis.

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We described the life cycles of 17 riffle-dwelling mayfly species in a central Japanese stream. Both species of Baetidae (Alainites yoshinensis Gose and Baetis thermicus Uéno) and two of nine species of Heptageniidae (Ecdyonurus scalaris Kluge and Epeorus latifolium Uéno/l-nigrus Matsumura) in this stream were multivoltine (more than one generation per year). Seven other heptageniid species (two unidentified species of Cinygmula, Epeorus aesculus Imanishi, E. curvatulus Matsumura, E. ikanonis Takahashi, E. napaeus Imanishi, and Rhithrogena japonica Uéno) and all six species of Ephemerellidae [Cincticostella elongatula (McLachlan), C. nigra (Uéno), Drunella basalis (Imanishi), D. ishiyamana Matsumura, D. sachalinensis (Matsumura), and D. trispina (Uéno)] were essentially univoltine.

In recent years, insecticide trunk injection was put into practical use for controlling wood boring pests. However, few studies have investigated the dose–response relationships between insecticides and wood–boring pests in detail. This study used two commercial formulations of the neonicotinoid insecticides thiamethoxam and dinotefuran and investigated their dose–response relationships with invasive wood borer Aromia bungii (Coleoptera: Cerambycidae) larvae. Neonates and late instar larvae were reared with an artificial diet containing different insecticide concentrations (0.01–100 ppm) in the laboratory, and their diet excavation activity, survival rate, and weight change were recorded. Diet excavation immediately dropped in larvae exposed to high concentrations of thiamethoxam or dinotefuran (≥1 ppm in neonates and ≥10 ppm in late instar larvae). The weight and survival rate gradually declined over 12 weeks in late instar larvae. These results suggest that the two neonicotinoids intoxicate and debilitate A. bungii larvae gradually to death. In practical use, rapid suppression of A. bungii wood boring damage can be expected by trunk injection of neonicotinoid insecticides. However, a relatively long-term retention of the insecticides may be required to kill large larvae. Neonates may be controlled with lower insecticide dosage and shorter exposure than larger larvae.

Aromia bungii (Faldermann) (Coleoptera: Cerambycidae) is an invasive pest, damaging Rosaceae trees (particularly Prunus) in Japan and Europe. The establishment of this beetle in Japan was first detected in 2012, and subsequently, it has rapidly expanded its distribution. Currently, Japanese populations of A. bungii are widely distributed in six non-contiguous regions. In this study, we compared the nucleotide sequences of mitochondrial cytochrome oxidase subunit 1 of the populations in these six regions in Japan to examine whether multiple introductions or human-mediated long-distance dispersal have contributed to the non-contiguous distribution of A. bungii. Seven haplotypes were detected from Japanese populations, and one of these was identical to a sequence deposited from China. One to two haplotypes were detected in each region, suggesting a genetic bottleneck. Detected haplotypes differed between introduced regions, although two regions shared a single haplotype. These results suggest that multiple independent introductions of A. bungii have contributed to its non-contiguous distribution in Japan. Quarantine measures for wood-packing materials in trade need to be strengthened to prevent the establishment of further populations of A. bungii.